Field of the Invention
The invention relates to a torque support for a valve lock in order to prevent a rotation of the lock with respect to the valve.
Discussion of the Prior Art
Valve lock systems perform the task of preventing the valve from being actuated in an unauthorized manner to prevent an unauthorized change to the state of the valve.
These locking systems are therefore inserted as a separate component between the valve and the valve actuator, wherein this separate component substantially comprises or impinges on the interfacing means between the valve actuator, e.g. a hand wheel or a hand lever, and the valve stem.
Valve locking systems or respectively the torque supports thereof and adapters for manually operated valves are required for adapting to the wide range of valves in various designs which are being used. Adapters of the locking systems have to be adapted to the different stem shapes. The normal case is one where the end position can be set in said locking systems. The positions “valve completely open” and “valve completely closed” are frequently selected as the end position, wherein however other valve positions are also possible.
The interface between the valve stem and the actual lock of the locking system occurs, e.g., thereby via a hollow shaft, on the outside of which teeth for a retaining pawl are situated and in the end regions of which receptacles for adapters are located, which on the one hand are used to connect the stem and on the other hand are used to connect the hand wheel or the actuating lever.
Valve locking systems are also used everywhere, where an operational sequence for the valves contributes to an increase in personal and facility safety. Such facilities frequently include off shore oil rigs, chemical plants and oil refineries, those of the gas industry, as well as nuclear power plants.
A torque support generally serves the purpose of preventing a rotation of the valve lock with respect to the valve. This is also important for the reason of securing the end-position setting of said valve lock. In the locked state, the torque support must intercept the torque during an unauthorized attempt to actuate the valve so that the entire lock on the valve cannot be rotated.
European patent publication EP 0 942 215 discloses a device that is a robust, heavy web. Said web is fixed to the valve lock overlaps the hand wheel and mounts to two brackets beneath said hand wheel, which encompass the valve or respectively the valve housing thereof like a clamp. These two clamps are screwed to one another and have to be adapted to the valve housing or the valve lever. This version is complicated to install and destroys the design of the lock per se.
WIPO patent publication WO 2009/026 905 A1, in which an adapter ring for connecting the torque support to the valve lock and two arresting rings that are located inside the adapter ring are provided, each arresting ring carrying a thrust bearing plate that extends downward. The thrust bearing plates only extend over part of the circumference of the arresting rings and can thus overlap either the pipe containing the valve slide or the sealing means or corresponding devices on the valve housing, by which the rotation of the valve lock is prevented. A plurality of locking screws is necessary and provided in said adapter ring for rotationally fixing the arresting rings. This arrangement is individually adapted to each valve design and can therefore not be manufactured in a prefabricated manner and requires a plurality of components comprising screws, tools and the like for installation.
U.S. Pat. No. 5,806,555 discloses a locking device for valves, which is not comparable with the locking system according to the European patent publication EP 0 942 215 A1 that can be actuated with a key. In this known apparatus, the lever actuating the valve slide is fixed in both end positions thereof, i.e., in the completely open position or in the completely closed position, by means of two overlapping brackets, which can be connected to one another and secured via padlocks. This system is only operational if the two padlocks are taken off, the two brackets are removed and the actuating lever for the valve slide is actuated. In this case, a connection therefore does not exist between the valve stem and the actual lock of the locking system, but rather the locking system referenced here must be completely dismantled if the actuating lever is to be operated. In these arrangements, it is not ensured that only a fixed operational sequence of the different valves to be actuated can be executed.
Valve locking systems normally work, as can be seen in the European patent publication EP 0 942 215 A1, with a plurality of locks and keys and the valve locks can only be actuated if both keys are in the lock. The keys are thereby individually coded.
A key having incorrect coding cannot be inserted into the lock or rather cannot release said lock. The respective keys can only be withdrawn if the valve is located in a certain position. If one key is withdrawn, the other key is then caught in the lock. It is usually the case that the key can only be withdrawn if the valve is completely open, and the other key can only be removed if the valve is completely closed. The arrangement known from the American patent publication U.S. Pat. No. 5,806,55 does not fulfill this requirement.
What is needed, therefore, is a torque support that results in low assembly costs, facilitates cost-effective production, and is able to be used with different valve types.